build: Add Coverity scan model

the modeling file help to avoid false positives and increase scanning
accuracy by explaining code Coverity can't see (out of tree libraries);
the model file must be uploaded by an admin to:
https://scan.coverity.com/projects/pulseaudio?tab=analysis_settings

the pa_assert_se() macro needs to be rewritten for Coverity so that
the assignment is not declared a side-effect

Signed-off-by: Peter Meerwald-Stadler <pmeerw@pmeerw.net>

coverity/model.c

@@ -0,0 +1,18 @@
+/* Coverity Scan model
+ * Copyright (C) 2017 Peter Meerwald-Stadler <pmeerw@pmeerw.net>
+ *
+ * This is a modeling file for Coverity Scan which helps to avoid false
+ * positives and increase scanning accuracy by explaining code Coverity
+ * can't see (out of tree libraries); the model file must be uploaded by
+ * an admin to:
+ * https://scan.coverity.com/projects/pulseaudio?tab=analysis_settings
+ */
+
+void fail(void) {
+    __coverity_panic__();
+}
+
+void fail_unless(int x) {
+    if (!x)
+        __coverity_panic__();
+}

src/pulsecore/macro.h

@@ -186,13 +186,22 @@ static inline size_t PA_ALIGN(size_t l) {
 
 /* pa_assert_se() is an assert which guarantees side effects of x,
  * i.e. is never optimized away, regardless of NDEBUG or FASTPATH. */
+#ifndef __COVERITY__
 #define pa_assert_se(expr)                                              \
     do {                                                                \
         if (PA_UNLIKELY(!(expr))) {                                     \
             pa_log_error("Assertion '%s' failed at %s:%u, function %s(). Aborting.", #expr , __FILE__, __LINE__, PA_PRETTY_FUNCTION); \
             abort();                                                    \
         }                                                               \
     } while (false)
+#else
+#define pa_assert_se(expr)                                              \
+    do {                                                                \
+        int _unique_var = (expr);                                       \
+        if (!_unique_var)                                               \
+            abort();                                                    \
+    } while (false)
+#endif
 
 /* Does exactly nothing */
 #define pa_nop() do {} while (false)